text: In 1868 Janssen discovered how to observe solar prominences without an eclipse. While observing the solar eclipse of 18 August 1868, at Guntur, Madras State (now in Andhra Pradesh), British India, he noticed bright lines in the spectrum of the chromosphere, showing that the chromosphere is gaseous.  Present in the spectrum of the Sun, though not immediately noticed or commented upon, was a bright yellow line later measured to have a wavelength of 587.49 nm. This was the first observation of this particular spectral line, and one possible source for it was an element not yet discovered on the earth.  From the brightness of the spectral lines, Janssen realized that the chromospheric spectrum could be observed even without an eclipse, and he proceeded to do so.
  On 20 October, Joseph Norman Lockyer in England set up a new, relatively powerful spectroscope.  He also observed the emission spectrum of the chromosphere, including the same yellow line. Within a few years, he worked with a chemist and they concluded that it could be caused by an unknown element, after unsuccessfully testing to see if it were some new type of hydrogen. This was the first time a chemical element was discovered on an extraterrestrial body before being found on the earth.  Lockyer and the English chemist Edward Frankland named the element after the Greek word for the Sun, ἥλιος (helios).
  , distinguishing it from the nearby D and D doublet lines of sodium. He and English chemist Edward Frankland named the element after the Greek word for the Sun god, Helios. -->